U.S. Pat. No. 8,008,845 B2 discloses a lighting device in the form of an encapsuled LED arranged in a transparent heat sink with a back reflector and a positive and a negative terminal on the front side. Light emitted by the LED passes through at least a part of the transparent heat sink before exiting the lighting device.
High brightness light sources are interesting for various applications including spots and digital light projection. For this purpose, it is possible to make use of light guides in which shorter wavelength light is converted to longer wavelengths in a highly transparent luminescent material. A light guide of such a transparent luminescent material is illuminated by LEDs to produce longer wavelengths within the light guide. Converted light which is in the light guide can then be extracted from one of the surfaces thereby leading to an intensity gain.
It is thus desired to increase the light density falling onto the light guide in order to obtain higher output intensity. However, the distribution and spreading of the heat dissipated inside the light guide limits the maximum obtainable light intensity severely.
Also, the excess heat will lead to a poor optical performance, for example due to thermal quenching, and might cause reliability issues.
EP2346101A1 discloses a light emitting module wherein an optical wavelength conversion ceramic, provide with a reflective film, converts the wavelength emitted by a semiconductor light emitting element. The emission area of the light which passed through the optical wavelength conversion ceramic is narrowed to be smaller than the light emission area of the semiconductor light emitting element. The reflective element guides the light so that light is emitted roughly parallel to the light emitting surface of the semiconductor light emitting element.